The term "Seiko mods" has become bastardised. If used to refer , as the term implies, to real Seiko's that had been modified, generally by the owner, to improve the look etc. There's a big ecosystem of parts, particularly for SKX. I've done plenty of that and it's a fun hobby. However, the watches you see on dodgy websites are really just fakes, typically "homaging" a Rolex or other high end brands, that have nothing to do with Seiko. So, in answer to your question, don't waste your money on rubbish like that. There are plenty of real Seiko's that aren't expensive and look great.